Exactly, you just hang onto your baggage and ask at Guest Services where to assemble early the next morning, to be assured of getting off first. You might get a couple of different answers, we did,
so we just scouted out the lounge closest to the gangway and hung outside next am. Those that went inside and made themselves comfortable, arrived early, but eventually were the last of our group to get off, as by the time the gangway was opened, the lounge was packed and they were then at the back of the line! You have to be able to handle your luggage by yourself, and have one hand free to hold the escalator handrail. .. If you are loaded down with luggage, have carry on and multiple bags they will make you wait for an elevator down to Customs.
As far as what time you can disembark, note what the time of docking is, and allow an hour for Customs etc to check the ship and allow passengers to start disembarking. That should be pretty close, but crew at the Gangway might have more information on the day.